The mission objectives of GFO-1 (GEOSAT FOLLOW-ON-1) program the U.S. Navy's initiative to develop an operational family of radar altimeters satellites to maintain continuous ocean observation from ... the GEOSAT exact repeat orbit. GFO-1 data will be used for precise measurement of both mesoscale and basin-scale oceanography. The length and time scales of these processes are too large for conventional in-the-water oceanographic instrumentation configurations to measure. Satellite altimetry is the only known method by which oceanographers can precisely measure sea surface topography. The shape of the sea surface is the only physical variable directly measurable from space that is directly and simply connected to the large-scale movement of water and the total mass and volume of the ocean.